Torque transmitting device

ABSTRACT

A torque transmitting device in which a plurality of fibers extend perpendicularly from one of a pair of normally opposed, generally parallel surfaces to engage circumferentially spaced protuberances defining the other surface. The torque transmitting surfaces are defined on a pair of relatively rotatable members and the extent of fiber engagement is adjustable to permit adjustment of the torque transmitted between the members by engagement of the fibers with the protuberances upon relative rotation of the members.

United States Patent Grundman [151 3,654,777 [451 Apr. 11, 1972 [54]TORQUE TRANSMITTING DEVICE [72] Inventor: Roger V. Grundman, Roseville,Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul,Minn.

[22] Filed: Nov. 25, 1970 [21] Appl.No.: 92,761

[52] US. Cl....l ..64/30, 74/214, 192/107 M [51] Int. Cl ..F16d 7/02[58] Field of Search ..64/30, 28 F; 74/214, 215;

[56] References Cited UNITED STATES PATENTS 2,655,241 10/1953 Hultberg..64/30 R 3,434,577 3/1969 Mathison ..l92/l07M Primary ExaminerEdward G.Favors Attomey-Kinney, Alexander, Sell, Steldt & Delahunt 57 ABSTRACT Atorque transmitting device in which a plurality of fibers extendperpendicularly from one of a pair of normally opposed, generallyparallel surfaces to engage circumferentially spaced protuberancesdefining the other surface. The torque transmitting surfaces are definedon a pair of relatively rotatable members and the extent of fiberengagement is adjustable to permit adjustment of the torque transmittedbetween the members by engagement of the fibers with the protuberancesupon relative rotation of the members.

23 Claims, 7 Drawing Figures PATENTEDAPR 11 1912 3,654,777

sum 2 [IF 2 INVENTOR. ROGER G u/vo/wA/v BYK M M/izlwfim A T TOANF'YS Thepresent invention relates to a torque transmitting device in whichfibers extending perpendicularly from one member engage protuberancesdefining a torque transmitting surface of a second relatively rotatablemember.

Torque transmitting devices have utilized both straight and specialformed fibers. In the prior art, fibers extending from one torquetransmitting member have generally engaged fibers of the same typeextending from a second member as disclosed in US. Pat. No. 2,424,873;2,941,410 and 3,143,895. Very little torque is transmitted betweenflexible fibers that extend perpendicularly from facing torquetransmitting surfaces since the fibers tend to brush past one anotherrather than engaging. For this reason, US. Pat. No. 2,424,873 disclosesthe use of stiff fibers such as metal fibers; U.S. Pat. No. 2,941,410discloses the use of straight fibers specially arranged on the torquetransmitting surfaces; and US. Pat. No. 3,143,895 discloses the use offibers specially formed for engagement. However, these have beendisadvantageous in that the first leaves little flexibility of choice offibers without sacrificing efficiency, the second requires specialmanufacturing equipment to arrange the fibers after they have beenflocked normal to the torque transmitting surfaces, and the thirdrequires special manufacturing equipment to form the fibers.

SUMMARY OF THE INVENTION The present invention provides a torquetransmitting device comprising a pair of relatively rotatable membershaving spaced, generally parallel torque transmitting surfaces. A plurality of short, elastic, normally straight fibers are secured to one ofthe surfaces and extend perpendicularly therefrom generally equaldistances greater than the minimum spacing between the torquetransmitting surfaces. A plurality of protuberances circumferentiallyspaced with respect to the axis of rotation of the members define theother of the torque transmitting surfaces. Upon relative rotation of themembers the fibers engage the protuberances and transmit torque betweenthe members through the resistance of the fibers to bending. The extentof fiber engagement is made adjustable and for each setting there is acorresponding limiting torque which may be transmitted between themembers.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a side elevational view of one embodiment of a torquetransmitting device constructed in accordance with the present inventionand partially in section;

FIG. 2 and 3 are perspective views of parts of the device of FIG. 1;

FIG. 4 is a cross section view of a portion of the device of FIG. 1;

FIG. 5 is a side elevation view of a second embodiment of a torquetransmitting device constructed in accordance with the present inventionand partially in section; and

FIGS. 6 and 7 are perspective view of parts of the device of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS j Referring now to FIGS. 1-4there is illustrated a first embodiment of a torque transmitting device,generally designated 10, constructed in accordance with the presentinvention and comprising a first torque transmitting member 12 and asecond torque transmitting member 14 having spaced, parallel, opposed,facing generally planar torque transmitting surfaces.

The first torque transmitting member 12 has the shape of a circulardisk, one face of which defines its torque transmitting surface, with ahollow cylinder extending coaxially from the opposite face of the disk.In the illustrated embodiment a generally uniform pattern ofprotuberances circumferentially spaced with respect to the axis of thefirst member 12 is defined by a regular woven screen 16, preferably of a16 to 40 mesh, formed from metal filaments, preferably having a 5diameter of from 0.007 inch to 0.020 inch. In this embodiment the radialcomponent of each filament of the screen 16 serves as a torquetransmitting protuberance. The screen 16 is adhesively bonded to a soliddisk which with the hollow cylindrical portion of the first member 12may be molded from a thermoplastic material. However, the entire firsttorque transmitting member 12 may also be a single piece thermoplasticmolding with the torque transmitting surface thereof embossed to definethe circumferentially spaced protuberances as radial ribs, a mesh orother similar patterns.

The second torque transmitting member has the shape of a disk with asolid circular cylinder extending perpendicularly centrally from itstorque transmitting surface. The first torque transmitting member isformed with a central circular aperture l3 and the cylindrical portionof the second torque transmitting member 14 is formed to extendcoaxially therethrough and through an aperture 21 fomied in a supportwall 20. The free end of the cylindrical portion extending through thesupport wall 20 is threaded, a helical compression spring 22 is placedthereover and an adjusting nut 24 is turned onto the threaded portion tocompress the spring 22.

A plurality of short, elastic, normally straight fibers 17 are securedto the torque transmitting surface of the second member 14 and extendperpendicularly therefrom. In the illustrated embodiment the fibers 17are embedded in an adhesive set on a fabric base and the composite isadhesively bonded to a torque transmitting surface of the second member14. This permits the fibers to be flocked and bonded onto the fabricbase in a conventional manner. The fibers preferably have a length offrom 0.080 inch to 0.250 inch and are 30 denier to 500 denier for nylon,polyester and like fibers or 0.001 inch to 0.010 inch in diameter formetal fibers. The fiber density is preferably from 200 to 14,000 fibersper square inch and the density is preferably inversely related to thefiber diameter chosen.

A drive or holding shaft 26 is secured coaxially with the second member14 in a recess formed therein. This shaft 26 permits driving of thesecond member 14 or alternatively it permits the second member 14 to beheld against rotation.

In use, the cylindrical portion of the first torque transmitting member12 may define a pulley in a drive system around which a belt may extendto drive it. The shaft 26 secured to the second torque transmittingmember 14 may be held stationary whereby the torque transmitting device10 acts as a rotational brake. Driving of the first member 12 will causeit to rotate with respect to the second member 14 and the fibers 17 willbe flexed into and out of the openings in the wire screen 16. Some ofthe rotational energy of the first member 12 will then be dissipated inflexing the fibers 17 due to the resistance of each fiber to bendingunder the force of a bending moment. Depending upon the bending strengthof the fibers chosen there will be a limit on the amount of rotationalenergy which can be dissipated. The limiting torque that is transmittedby engagement of the fibers with the mesh is adjustable by tuming thenut 24 to adjust the depth of penetration of the fibers 17 through themesh 16. The flexure of the fibers during torque transmission provides aself-cleaning action to assure consistency of torque transmission andthe provision of a high density of fibers assures that a generallyconstant number of fibers will at all times be in engagement therebyassuring a constant torque transmission.

With the first member 12 driven as described above, the shaft 26 may,alternatively, form a drive shaft to transmit torque to a secondaryportion of the drive system. In this case with each setting of theadjustment nut 24 there will be an associated constant limiting torquetransmission from the first member 12 to a second member 14 through thefibers 17.

Because the bending strength of the fibers 17 is a constant, the torquerequired to be applied to the first member 12 to start its rotationrelative to the second member 14 is generally the same as that requiredto continue the relative rotation, it only being necessary to overcomethe relatively small inertia] energy of the parts to start the rotation.This is highly advantageous over those torque transmitting devices usingsliding contact surfaces in which the coefficient of static friction isalways greater than that of dynamic friction thereby requiring a muchhigher torque to initially cause relative rotation between the members.

Referring now to FIGS. 5-7 there is illustrated a second embodiment of atorque transmitting device, generally designated 30, constructed inaccordance with the present invention and comprising a first torquetransmitting member 32 and a second torque transmitting member 34 havingspaced, generally parallel, nonnally opposed torque transmittingsurfaces.

The first torque transmitting member 32 has the shape of a hollowcylinder having one end closed and a drive or holding shaft 36 extendingcoaxially from the exterior surface of the closed end of the cylinder.As in the first embodiment, a generally uniform pattern of protuberancescircumferentially spaced with respect to the axis of the first member 32is defined by a regular woven screen 37, preferably like that describedwith reference to the first embodiment. The screen 37 is secured to thecurved inner surface of the cylindrical portion of the first member 32with the torque transmitting filaments thereof parallel to the axis ofthe cylindrical portion to define the torque transmitting surface of thefirst member.

The second torque transmitting member 34 is supported coaxially with thefirst member 32 and it has the shape of a solid cylinder with a drive orholding shaft 39 extending coaxially from one end of the cylindricalportion. The solid cylindrical portion of the second member 34 has adiameter less than the internal diameter of the torque transmittingsurface of the first member 32. A plurality of fibers 41 like thosedescribed with reference to the first embodiment are secured to thecurved torque transmitting surface of the cylindrical portion of thesecond member 34 preferably in a manner as described with reference tothe first embodiment. The fibers 41 extend perpendicularly from thetorque transmitting surface of the second member 34 generally equaldistances.

The first and second torque transmitting members 32 and 34 are supportedwith their torque transmitting surfaces normally directly opposed.Through support of their drive or holding shafts 36 and 39, the firstand second members 32 and 34 are supported for relative rotation totransmit torque between the members and for relative axial movement topermit a relative offsetting of the torque transmitting surfaces asillustrated in FIG. 5 and thereby to adjust the extent of the engagementof the fibers 41 with the screen 37 and the limiting torque that can betransmitted between the members.

In use, as with the first embodiment, the drive or holding shafts 36 and39 of the torque transmitting members 32 and 34 may be elements in adrive system. With one of the shafts 36 or 39 held stationary and theother shaft driven, the device serves as a constant limiting torquerotational brake in the same manner as described with reference to thefirst embodiment. With both shafts 36 and 39 rotatable, the deviceserves as a constant limiting torque transmitting device also asdescribed with reference to the first embodiment. In either arrangementthe constant limiting torque may be adjusted by relative axial movementof the members to cause offsetting of the torque transmitting surfaces,the greatest limiting torque for a specific device being attained whenthe torque transmitting surfaces are directly opposed.

Having described the present invention with reference to two preferredembodiments it is to be understood that minor modifications may beaffected without departing from the spirit or scope of the presentinvention.

I claim: 1. A torque transmitting device comprising: a a pair ofcoaxially supported members having surfaces, at least one of saidmembers being supported for rotation about the common axis,

a plurality of short, elastic, normally straight fibers secured to oneof said torque transmitting surfaces and extending generallyperpendicularly therefrom generally equal distances greater than theminimum spacing between said torque transmitting surfaces, and

a plurality of protuberances circumferentially spaced with respect tosaid common axis of said members to define the other of said torquetransmitting surfaces,

whereby upon relative rotation of said members said fibers engage saidprotuberances to transmit torque between said members through theresistance of said fibers to bending.

2. A torque transmitting device as recited in claim 1 including meansfor adjusting the extent of engagement of said fibers with saidprotuberances to permit adjustment of the torque that may be transmittedbetween said members.

3. A torque transmitting device as recited in claim 1 wherein saidprotuberances define a generally uniform pattern torque transmittingsurface.

4. A torque transmitting device as recited in claim 3 wherein saidprotuberances are defined by a regular woven mesh secured to a generallysolid support surface.

5. A torque transmitting device as recited in claim 4 including meansfor adjusting the extent of engagement of said fibers with saidprotuberances to permit adjustment of the torque that may be transmittedbetween said members.

6. A torque transmitting device as recited in claim 1 wherein said othermember is supported against rotation to form a constant limiting torquerotational brake.

7. A torque transmitting device as recited in claim 1 wherein said othermember is independently supported for rotation about said common axis toform a constant limiting torque slip clutch.

8. A torque transmitting device comprising:

a pair of members having spaced, generally parallel, facing torquetransmitting surfaces, at least one of said members being supported forrotation about an axis generally perpendicular to said torquetransmitting surfaces,

a plurality of short, elastic, normally straight fibers secured to oneof said torque transmitting surfaces and extending perpendicularlytherefrom generally equal distances greater than the minimum spacingbetween said surfaces, and

a plurality of protuberances circumferentially spaced with respect tosaid axis to define the other of said torque transmitting surfaces,

whereby upon rotation of said one member said fibers engage saidprotuberances to transmit torque between said members through resistanceof said fibers to bending.

9. A torque transmitting device as recited in claim 8 including meansfor adjusting said spacing between said facing planar surfaces to permitadjustment of the torque that may be transmitted between said members.

10. A torque transmitting device as recited in claim 8 wherein saidprotuberances define a generally uniform pattern torque transmittingsurface.

11. A torque transmitting device as recited in claim 10 wherein saidprotuberances are defined by a regular woven mesh secured to a generallysolid planar support surface.

12. A torque transmitting device as recited in claim 11 including meansfor adjusting said spacing between said facing planar surfaces to permitadjustment of the torque that may be transmitted between said members.

13. A torque transmitting device as recited in claim 12 wherein saidmeans for adjusting said spacing includes resilient means for urgingsaid members together to urge the free ends of said fibers through saidmesh into contact with --said solid support surface.

spaced, it generally parallel, normally opposed torque transmitting 14.A torque transmitting device as recited in claim 8 wherein said membersare disk-shaped and coaxial.

15. A torque transmitting device as recited in claim 8 wherein saidother member is supported against rotation to form a constant limitingtorque rotational brake.

16. A torque transmitting device as recited in claim 8 wherein saidother member is independently supported coaxially with said first memberfor rotation about the common axis to form a constant limiting torqueslip clutch.

17. A torque transmitting device comprising:

a pair of coaxially supported interfitting cylinders having curved,spaced, generally parallel, normally opposed torque transmittingsurfaces, at least one of said members being supported for rotationabout the common axis,

a plurality of short, elastic normally straight fibers secured to one ofsaid torque transmitting surfaces and extending generallyperpendicularly therefrom generally equal distances greater than theminimum spacing between said torque transmitting surfaces, and

a plurality of protuberances circumferentially spaced with respect tosaid common axis of said members to define the other of said torquetransmitting surfaces,

whereby upon relative rotation of said members said fibers engage saidprotuberances to transmit torque between said members through theresistance of said fibers to bending.

18. A torque transmitting device as recited in claim 17 including meansfor effecting relative axial movement of said members to permit relativeoffsetting of said torque transmitting surfaces to adjust the extent ofengagement of said fibers with said protuberances and the torque thatmay be transmitted between said members.

19. A torque transmitting device as recited in claim 17 wherein saidprotuberances define a generally uniform pattern torque transmittingsurface.

20. A torque transmitting device as recited in claim 19 wherein saidprotuberances are defined by a regular woven mesh secured to a generallysolid support surface.

21. A torque transmitting deviceas recited in claim 20 including meansfor effecting relative axial movement of said members to permit relativeoffsetting of said torque transmitting surfaces to adjust the extent ofengagement of said fibers with said protuberances and the torque thatmay be transmitted between said members.

22. A torque transmitting device as recited in claim 17 wherein saidother member is supported against rotation to form a constant limitingtorque rotational brake.

23. A torque transmitting device as recited in claim 17 wherein saidother member is independently supported for rotation about said commonaxis to form a constant limiting torque slip clutch.

1. A torque transmitting device comprising: a pair of coaxiallysupported members having spaced, generally parallel, normally opposedtorque transmitting surfaces, at least one of said members beingsupported for rotation about the common axis, a plurality of short,elastic, normally straight fibers secured to one of said torquetransmitting surfaces and extending generally perpendicularly therefromgenerally equal distances greater than the minimum spacing between saidtorque transmitting surfaces, and a plurality of protuberancescircumferentially spaced with respect to said common axis of saidmembers to define the other of said torque transmitting surfaces,whereby upon relative rotation of said members said fibers engage saidprotuberances to transmit torque between said members through theresistance of said fibers to bending.
 2. A torque transmitting device asrecited in claim 1 including means for adjusting the extent ofengagement of said fibers with said protuberances to permit adjustmentof the torque that may be transmitted between said members.
 3. A torquetransmitting device as recited in claim 1 wherein said protuberancesdefine a generally uniform pattern torque transmitting surface.
 4. Atorque transmitting device as recited in claim 3 wherein saidprotuberances are defined by a regular woven mesh secured to a generallysolid support surface.
 5. A torque transmitting device as recited inclaim 4 including means for adjusting the extent of engagement of saidfibers with said protuberances to permit adjustment of the torque thatmay be transmitted between said members.
 6. A torque transmitting deviceas recited in claim 1 wherein said other member is supported againstrotation to form a constant limiting torque rotational brake.
 7. Atorque transmitting device as recited in claim 1 wherein said othermember is independently supported for rotation about said common axis toform a constant limiting torque slip clutch.
 8. A torque transmittingdevice comprising: a pair of members having spaced, generally parallel,facing torque transmitting surfaces, at least one of said members beingsupported for rotation about an axis generally perpendicular to saidtorque transmitting surfaces, a plurality of short, elastic, normallystraight fibers secured to one of said torque transmitting surfaces andextending perpendicularly therefrom generally equal distances greaterthan the minimum spacing between said surfaces, and a plurality ofprotuberances circumferentially spaced with respect to said axis todefine the other of said torque transmitting surfaces, whereby uponrotation of said one member said fibers engage said protuberances totransmit torque between said members through resistance of said fibersto bending.
 9. A torque transmitting device as recited in claim 8including means for adjusting said Spacing between said facing planarsurfaces to permit adjustment of the torque that may be transmittedbetween said members.
 10. A torque transmitting device as recited inclaim 8 wherein said protuberances define a generally uniform patterntorque transmitting surface.
 11. A torque transmitting device as recitedin claim 10 wherein said protuberances are defined by a regular wovenmesh secured to a generally solid planar support surface.
 12. A torquetransmitting device as recited in claim 11 including means for adjustingsaid spacing between said facing planar surfaces to permit adjustment ofthe torque that may be transmitted between said members.
 13. A torquetransmitting device as recited in claim 12 wherein said means foradjusting said spacing includes resilient means for urging said memberstogether to urge the free ends of said fibers through said mesh intocontact with said solid support surface.
 14. A torque transmittingdevice as recited in claim 8 wherein said members are disk-shaped andcoaxial.
 15. A torque transmitting device as recited in claim 8 whereinsaid other member is supported against rotation to form a constantlimiting torque rotational brake.
 16. A torque transmitting device asrecited in claim 8 wherein said other member is independently supportedcoaxially with said first member for rotation about the common axis toform a constant limiting torque slip clutch.
 17. A torque transmittingdevice comprising: a pair of coaxially supported interfitting cylindershaving curved, spaced, generally parallel, normally opposed torquetransmitting surfaces, at least one of said members being supported forrotation about the common axis, a plurality of short, elastic normallystraight fibers secured to one of said torque transmitting surfaces andextending generally perpendicularly therefrom generally equal distancesgreater than the minimum spacing between said torque transmittingsurfaces, and a plurality of protuberances circumferentially spaced withrespect to said common axis of said members to define the other of saidtorque transmitting surfaces, whereby upon relative rotation of saidmembers said fibers engage said protuberances to transmit torque betweensaid members through the resistance of said fibers to bending.
 18. Atorque transmitting device as recited in claim 17 including means foreffecting relative axial movement of said members to permit relativeoffsetting of said torque transmitting surfaces to adjust the extent ofengagement of said fibers with said protuberances and the torque thatmay be transmitted between said members.
 19. A torque transmittingdevice as recited in claim 17 wherein said protuberances define agenerally uniform pattern torque transmitting surface.
 20. A torquetransmitting device as recited in claim 19 wherein said protuberancesare defined by a regular woven mesh secured to a generally solid supportsurface.
 21. A torque transmitting device as recited in claim 20including means for effecting relative axial movement of said members topermit relative offsetting of said torque transmitting surfaces toadjust the extent of engagement of said fibers with said protuberancesand the torque that may be transmitted between said members.
 22. Atorque transmitting device as recited in claim 17 wherein said othermember is supported against rotation to form a constant limiting torquerotational brake.
 23. A torque transmitting device as recited in claim17 wherein said other member is independently supported for rotationabout said common axis to form a constant limiting torque slip clutch.